The invention relates to a steel section for the framing and stiffening of formwork panels which serve for the shuttering of concrete masses, having a protuberance which rests on the outer circumferential surface of the formwork panel with a first, short flange which forms a continuation of the protuberance and rests on the marginal zone of the inner side of the formwork panel, with a second, long flange which forms a continuation of the first flange, stands perpendicular to the formwork panel and has a shallow, V-shaped indentation pointing towards the internal space of the steel section, with a third, short flange which forms a continuation of the second flange and extends outwards lying parallel to the formwork panel and with a fourth flange which forms a continuation of the third flange and extends in the direction towards the protuberance.
Such a section has become known from Austrian Pat. No. 322,186. In this case, a wooden bar is pushed laterally into the open cavity of the steel section to prevent concrete from flowing into it. This steel section has the following disadvantages:
1. It has appeared in practice that the wooden bar swells due to moisture. The wooden bar is also slowly frayed under stress in practical work. Two steel sections are always pressed against one another in use, but the desired flat pressing surface is lacking under these conditions.
2. It is very difficult to introduce the wooden bar into the steel section.
3. The wooden bar must have a quite specific cross-sectional form.
4. If the wooden bar is not held by the flanges, it must be held by additional screws which exert an initial stress upon the steel section, require passage holes and form obstacles.
5. In relation to its length, the fourth flange contributes little to the rigidity of the steel section.
6. If after a period of use, the wooden bar lacks a part of its volume, then the wedge of the bracing device must be driven in substantially more than was originally intended. Then the originally intended abutment conditions for the wedge surfaces change.
7. The corner zone between the protuberance and the first flange is right-angled. Correspondingly, the external circumferential surfaces of the formwork panel must also be trimmed to right angles. Otherwise, it is not possible to turn the formwork panel around and arrange the outer surface, which is worn after some time, inwards and the as yet unworn, originally inner surface now outwards.
8. On the finished concrete wall a burr is always distinguishable corresponding to the double thickness of the protuberance.